48 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 3, 



But the country is well known, and its superficial features are approxi- 

 mately delineated in Mr. Greenough's Geological Map of England ; 

 and a geological map of the tract of country on the line of this 

 section, as well as of the section which immediately follows, has been 

 published in the Geological Transactions *, in illustration of a paper 

 by Mr. Phillips, before alluded to ; and to this map I may refer the 

 reader. 



The carboniferous and nearly horizontal rocks of Penygent are 

 well known. The top of the mountain represents a part of the Mill- 

 stone-grit series (see fig. 5). In the steep brows below, we have 

 alternations of limestone, sandstone, and shale (the Limestone Shale 

 of Derbyshire or the Yordale Series of Phillipsf ). Near the base 

 of the mountain is the great Scar-limestone, overlying (as in the two 

 former sections, figs. 3 & 4) the highly-inclined beds of older slate- 

 rocks (fig. 5, d, e). These older rocks have a structure almost identical 

 with that of the rocks under Thornton Force and Twisleton Scar. 

 Over them are beds of the Horton flagstone (fig. 5, c) ; and at Stud- 

 gill, about a mile below Horton, some of the beds are covered by in- 

 numerable specimens of Graptolites Sagittarius, which fossil I had 

 formerly mistaken for Graptolites Ludensis. But I profess not to 

 describe the section in any detail, as I made no observations worth 

 recording in a traverse down the east side of the Ribble. My only 

 object in giving this (partly ideal) section is to show the grand cross- 

 fault, at Stainforth, which brings down the great Scar-limestone, 

 alters the superficial features of the country, and shuts out the slate- 

 rocks from all the lower parts of the valley. 



Section from the top of Penygent, in Craven, over Moughton Fell, 

 thence over the calcareous ridge west of Austwick, and across the 

 line of the Craven fault to the plains immediately south of Clapham. 

 Fig. 6, p. 47. — 1. The carboniferous, and nearly horizontal, strata of 

 Penygent (figs. 5 & 6, 4, 5, e) have been just noticed. 



2. At Dowgill Scar, a few hundred yards above the village of 

 Horton, the slate-rocks break out at the base of the Scar Limestone ; 

 and, at the spots where I examined the junction of the two systems, 

 there was no trace of any intervening conglomerates to represent the 

 old-red-sandstone. This slate-group, although partially repeated by 

 undulations, is of considerable thickness ; but it disappears under the 

 alluvion of the valley before we reach the village. I had many times, 

 before last summer, seen these beds, but I never before examined 

 them carefully, or with any view of comparing them with other de- 

 posits of the same age. Considered as a group, I was at once struck 

 with their resemblance to the upper portion of the old groups of rock 

 in the two preceding sections (of Thornton Beck and Ingleton Beck, 

 figs. 3 & 4), between the slate-quarries and the spots where the slates 

 plunge under the tilted beds of the Scar-limestone. For in this part 

 of the Horton rivulet we remark the same frequent appearance of 

 chloritic colour, the same hard greenish-blue calliards, the same im- 

 perfect slaty cleavage, and a similar aggregation of calcareous matter 



* 2 Ser. vol. iii. 



t See Illustr. Geol. Yorkshire, Part 2. 



